This invention is directed to an apparatus and method for heating fat tissues for medical purposes, such as body contouring and weight reduction by removal of unwanted fatty deposits.
Obesity is one of the most common conditions experienced by men and women in the United States and it is rapidly becoming a worldwide phenomenon. Obesity is generally defined as being overweight by 30% or more; 100% overweight is quite common; and 200% overweight is not rare. One case of 500% overweight has been treated surgically, with removal of 150 kilograms of fat in one procedure. Since the advent of liposuction, there has been a steady world wide growth of cosmetic surgery, now accelerated by the addition of the ultrasonic procedure, to several hundred thousand surgeries per year.
Obesity is a condition which arises from the natural bodily function of storing energy from food ingested during excess availability, to provide for times of shortage. To some extent, the body will attempt to store fat without limit. Huge amounts of money are expended to remove fat by diet, exercise, and surgery. Dieting is generally unsatisfactory, because it is very reversible; exercise is slow and repugnant to many. Surgery is a faster solution, but traumatic, and, if used to excess, can be life threatening.
Initially, the popular practice in liposuction surgery was to use a vacuum aspiration source connected to a tube, or cannula, fitted with a handle, and to plunge the cannula, in a tunneling mode, vigorously into the body where fat deposits were to be removed. The physical damage to the fatty tissue liberated fat and blood in approximately equal quantities. Most recipients of this treatment did so for cosmetic improvement, or contouring. An improvement of the procedure was disclosed in U.S. Pat. No. 4,886,491, in which ultrasonic energy was supplied to the cannula, making the liberation of fat significantly less traumatic, because of a reduction in the loss of blood, better fat cell melting/liquefaction, and less tissue damage. This has enabled greater quantities of fat to be aspirated, with a limited amount of trauma, and it has reduced the physical effort required of the surgeon, since the cannula tends to part the tissue as it penetrates. In both the original and the ultrasonic-aided liposuction procedures, fat cells are removed so that they are no longer available as locations for the storage of fat. Unless the body generates more fat cells, the reduction of fat storage capability is permanent.
Fatty tissue is made up of an ensemble of small vesicles, or adipocytes, each having a wall of protein forming a "skin". Adjacent adipocytes appear to share these walls in such a way as to form a larger structure, similar to a foam. These can vary from 1/10 mm to several millimeters in diameter. If the wall protein is removed, the reduction of fat storage capacity is permanent. If the wall protein is heated enough to "denature" the protein, such as in excess of 43.degree. C., the reduction is also permanent. If the wall is merely damaged, the potential exists for regeneration of the fat storage ability.
Recently, microwave treatment of tissue to curtail growth has been successfully demonstrated, for example, in cancerous tumors, benign tumors, and enlarged prostate glands, without damage to adjacent organs and without removal of the treated tissue. The denaturing of tissue in these examples is confined to the tissues targeted.